Image processing apparatus, printing system, image processing method, and program

Abstract

An image processing apparatus calculates a deformation direction and a deformation ratio of halftone dots, based on a printing condition including a printing direction, a printing speed and the like. Then, the image processing apparatus deforms halftone data, based on the calculated deformation direction and deformation ratio, and generates a halftone image by using the halftone data subjected to the deformation. The generated halftone image is composed of halftone dots deformed in accordance with the printing condition. Thus, the halftone dots are satisfactorily recorded on a printing sheet, and the density gradation of an image is accurately reproduced.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to an image processing technique for converting an input image into a halftone image.[0003]2. Description of the Background Art[0004]In printing for a printed material such as a newspaper, it has been conventional practice to convert an image to be printed into a halftone image to print the halftone image on a printing sheet. Conventional halftone dots include square, round and chain dots in shape, and are arranged at a predetermined density (or screen ruling) to form a lattice. For conversion of the image to be printed into the halftone image, halftone dots having sizes corresponding to the densities in respective positions of the image are arranged to generate the halftone image. The density gradation of the image is represented by a dot percentage in each of the positions of the halftone image.[0005]As discussed above, the density gradation of the image is represented by the dot percenta...

AI Technical Summary

Benefits of technology

[0009]The halftone image is composed of the halftone dots deformed in accordance with the printing condition. Thus, the halftone dots in the halftone image are satisfactorily recorded on a printing sheet, and the density gradation of the image is accurately reproduced.

[0026]It is therefore an object of the present invention to provide a technique capable of avoiding a recording failure of fine halftone dots on a printing sheet to accurately reproduce the density gradation of an image.

Problems solved by technology

Unfortunately, there have been cases where fine halftone dots in the halftone image for a high-speed printed material such as a newspaper are not satisfactorily printed on a printing sheet. FIG. 8 shows an example of fine halftone dots Ha recorded on a printing sheet P transported at a high speed.

In such cases, the density gradation of the image is not accurately reproduced on the printing sheet P, and the quality of the image deteriorates.

In particular, the higher screen ruling of the halftone image causes the smaller size of each halftone dot in the halftone image, to make it difficult to accurately reproduce the density gradation of the image.

The above-mentioned problem not only arises when the printing speed is high but also is sometimes caused by the grain roughness of the printing sheet and other printing conditions.

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